EP3262995B1 - Coffee machine, milk foaming ystem and milk foaming method - Google Patents

Description

The invention relates to a coffee machine according to the preamble of claim 1 with a milk frothing device, wherein the milk froth of a further beverage component, namely coffee, can be added, and wherein the coffee machine has an injection unit for leaching and / or dissolving beverage substrate provided in beverage substrate capsules or an integral grinder and a Brewing unit in which coffee grounds produced from coffee beans by the grinder can be leached (leached), the milk frothing device having a mechanical, dynamic emulsifying device and a stator and a rotor which can be driven rotatably relative to the stator about an axis of rotation, the emulsifying device comprising milk and air can be supplied on the inlet side and can be exposed to shear forces through rotation of the rotor relative to the stator and milk foam can thereby be generated, the milk foam being divertable on the outlet side, and where for generating the (on the milk and the air wi rkenden) shear forces, both the rotor and the stator have multiple shear element rows (preferably each arranged in a circular ring) comprising shear element rows, the shear element rows of the rotor and the shear element rows of the stator intermittently interlocking in such a way that the milk and air flowing through the intermittent shear element rows each time the rotor rotates can be or are sheared between one of the rows of shear elements of the rotor and an immediately adjacent row of shear elements of the stator.

The invention also relates to a milk frothing system according to claim 11 and to a milk frothing method according to the preamble of claim 12, wherein milk and air through a mechanical emulsifying device comprising a stator and a relative to the stator around a Rotation axis rotatably driven rotor are promoted, wherein in the emulsifying device rows of shear elements of the rotor and rows of shear elements of the stator intermesh in such a way that the milk and air flowing through the intermittent shear elements between one of the shear element rows of the rotor and an immediately adjacent shear element rows of the Stator are sheared.

From the WO 2015/082391 A1 a milk frothing device is known in which the rotor and stator interlock axially and the rows of shear elements of the rotor and the rows of shear elements of the stator are arranged alternately in the radial direction, so that the milk, depending on the supply radially inward or radially outward, the rows of shear elements in the radial direction outward or inward happened. The known milk frothing device has disadvantages. Because of the essentially cylindrical disk-shaped shape inherent in the principle, with a small length and a diameter that is large in relation to it, it is difficult to integrate into beverage preparation devices such as coffee machines. It is also felt to be disadvantageous that the shear effect is different in the radial direction from shear gap to shear gap due to the different angular velocity in the radial direction. In addition, the known milk frothing device is in need of improvement with regard to its cleanability, since different flow velocities result due to the different angular velocities and flushing out is likely to be difficult, especially in a large or outer diameter range with radial flow conditions.

From the unfamiliar DE 39 18 268 C1 a device for the continuous freezing of edible foams is known, which is not for Production of milk foam by conveying milk and air through intermittent rows of shear elements is suitable.

Proceeding from the aforementioned prior art, the invention is based on the object of specifying a coffee machine with an improved milk frothing device that can be easily integrated into the housing of such coffee machines. Uniform shear conditions should preferably be given over the flow path. It is particularly preferred if the milk frothing device of the coffee machine is designed in such a way that it is easy to clean.

Furthermore, the object is to provide a correspondingly improved milk frothing system. The object is also to provide a correspondingly improved method for frothing milk.

This object is achieved with regard to the coffee machine with the features of claim 1, i.e. in a coffee machine of the generic type in that the rows of shear elements of the rotor and the rows of shear elements of the stator are arranged alternately along the axis of rotation. Such an improved milk frothing device preferably also comprises a drive, in particular an electric motor, for rotating the rotor.

With regard to the milk frothing system, the object is achieved with the features of claim 11 and with regard to the milk frothing method with the features of claim 12.

Advantageous further developments of the invention are specified in the subclaims.

All combinations of at least two of the features disclosed in the description, the claims and / or the figures fall within the scope of the invention.

In order to avoid repetitions, features disclosed in accordance with the device should also apply and be claimable as disclosed in accordance with the method. Likewise, features disclosed in accordance with the method should also apply and be claimable as disclosed in accordance with the device.

The invention leads to a beverage preparation device, namely a coffee machine with a milk frothing device according to the invention, wherein the milk foam produced can preferably be fed or added to a further beverage component, namely coffee. The beverage preparation device has an injection unit for displaying and / or dissolving beverage substrate provided in beverage substrate capsules or a brewing unit and an integral milk, coffee grounds produced from coffee beans by the integral grinder being leached or coffee being brewed in the brewing unit.

The invention is based on the idea of not arranging the shear element rows of rotor and stator to realize the intermittent arrangement or interaction (or at least not only) alternating in the radial direction as in the prior art, but axially along the axis of rotation, so that on one Shear element row of the rotor axially adjacent follows a shear element row of the stator and then again a shear element row of the rotor etc. This leads to the fact that the shear gaps formed or limited by a shear element row of the rotor and a shear element row of the stator are spaced axially over always one shear element row and the milk and air flow in the axial direction through the rows of shear elements from shear gap to shear gap and thereby an axial distance along the axis of rotation travel from inlet to outlet. At least a large part (> 50%) of the shear gaps preferably have the same gap width, but this is not mandatory. The inventive axial nesting or arrangement of the rows of shear elements of the rotor and stator one behind the other has considerable advantages. With regard to the structural shape, it is possible and preferably to provide an elongated milk frothing device which is arranged more in the form of a rod and is characterized by a comparatively large length or a small width or diameter. Such designs can be integrated comparatively easily in the housings of beverage preparation devices such as coffee machines. Another essential advantage is that (assuming that the shear gap has the same shear gap properties) the shear action in the different shear gaps is the same, since the problem of different angular speeds does not exist in different shear gaps. In any case, the shear action does not increase or decrease in the axial direction, at least not without special measures such as a change in the width of the shear gap, in the axial direction from shear gap to shear gap. In addition, the cleanability of a milk frothing device according to the invention is significantly improved since it can be flushed through axially. It is particularly useful if an inlet area has a diameter area that changes over its axial extent, the diameter preferably increasing in the inlet area in the direction of the shear element rows and / or the diameter in the outlet area decreasing in the axial direction away from the shear element rows.

Overall, the milk frothing device according to the invention, preferably not comprising a deep freezing device, offers at least one row of shear elements of the rotor in the axial direction sandwiched between two rows of shear elements of the stator and / or one row of shear elements of the stator in the axial direction along the axis of rotation The aforementioned advantages are sandwiched between two rows of shear elements of the rotor and can also be easily implemented in terms of construction, in particular if the rows of shear elements of the stator are arranged as radially inward projections on a stator body (preferably formed in one piece with these), which at the same time has an elongated housing function for has the emulsifying device, that is to say the emulsifying device or an emulsifying chamber of the emulsifying device is limited circumferentially and in the axial direction along the axis of rotation with a radial distance therefrom and the rotor is preferably inserted axially into this stator body. For this purpose, the rotor-side shear elements and the stator-side shear elements are arranged relative to one another in such a way that in at least one relative rotational position of the rotor relative to the stator, the shear elements of the rotor can be moved past in the circumferential direction between the shear elements of the stator in the axial direction in order to mount the rotor or to replace. In other relative rotational positions, the rotor is secured axially along the axis of rotation via axially adjacent shear elements of the stator. In the milk frothing device according to the invention, the milk and the air flow, as mentioned, in the axial direction from shear gap to shear gap running around the axis of rotation, with the rotation of the rotor and thus the rows of shear gaps relative to one another, the milk and the air constantly changing direction, especially in the axial direction / Circumferential direction are subject.

The milk foam resulting from the device according to the invention and the method according to the invention has a temperature of over 0 ° C, in particular over 5 ° C, very particularly preferably over 10 ° C. In order to produce hot milk foam, the milk is preferably heated in an area in front of the milk foaming device within the scope of the device, the method and the system, preferably to a temperature of over 40 ° C., even more preferably of over 50 ° C.

Preferably at least two, preferably more than two rotor-side shear element rows and at least two, preferably more than two stator-side shear element rows, each comprising several circumferentially spaced, preferably radially adjustable, shear elements are provided. It is particularly expedient if at least three, preferably at least four, axially spaced rows of shear elements are provided on the stator and on the rotor. At least the majority of the shear gaps preferably have the same external diameter.

An embodiment of the milk frothing device is particularly useful in which the rows of shear elements of the rotor comprise a plurality of shear elements spaced apart in the circumferential direction around the axis of rotation, in particular in the form of radial extensions, preferably formed in one piece with a rotor body, which extend from the rotor body extending along the axis of rotation of the rotor in the radial direction, in particular from radially inside to radially outward, such that the milk and air can flow along the axis of rotation between two of the circumferentially adjacent shear elements of a shear element row to the axially adjacent shear element row of the stator.

In addition or as an alternative, a further development of the invention advantageously provides that the rows of shear elements of the stator each comprise a plurality of shear elements which are spaced apart in the circumferential direction about the axis of rotation and which extend from a preferably hollow cylindrical stator body (in particular housing of the emulsifying device, which extends along the axis of rotation) Emulsifying chamber limited radially on the outside) of the stator in the radial direction, in particular from radially outside to radially inward, in such a way that the milk and the air axially along the axis of rotation between in each case two in the circumferential direction adjacent shear elements flow to the axially adjacent row of shear elements of the stator (can). In principle, it is possible if only some of the shear element rows of the rotor and / or some of the shear element rows of the stator have several shear elements spaced apart in the circumferential direction - however, an embodiment is preferred in which all the shear element rows of the rotor and / or all the shear element rows of the stator such in the circumferential direction have spaced shear elements. An embodiment has previously been described as particularly advantageous in which the rotor is seated radially inside the stator and rotates relative to it. An alternative design provides for a radially inner stator around which the rotor, which is then designed as a hollow body, is arranged to rotate.

It has proven to be particularly expedient if an inlet side, on which milk and air are supplied, and an outlet side, from which the (finished) milk foam is derived, are axially spaced from one another along the axis of rotation over the majority of the rows of shear elements, in particular over all the rows of shear elements, that is to say that the supply of milk and air takes place at one axial end and the milk foam is diverted at the opposite axial end. It has proven to be particularly useful if the supply line or the supply lines for milk and air as well as the discharge line are arranged at least approximately (axially spaced) in the same radial position, i.e. on the same diameter, but this is not mandatory.

Particularly preferred is an embodiment of the milk frothing device in which it is designed at the same time as a conveying device which automatically drives or transports the milk and air in the axial direction along the axis of rotation from row of shear elements to row of shear elements or from the inlet side to the axial spaced outlet side takes care, namely by the shear elements even because of their contouring in combination with the rotational movement, in particular in the manner of turbine blades, drive the fluid or fluids in the axial direction through the emulsifying device. As will be explained later in the context of a milk frothing system comprising a milk frothing device according to the invention, this opens up the possibility of dispensing with a separate conveying device, in particular a milk conveying pump, and realizing the milk conveying solely with the help of the milk frothing device or its, in particular turbine-like shaped shear elements. A combined milk and air delivery can be achieved, for example, in that at least some of the rotor-side shear elements, preferably over most of their respective axial extent along the axis of rotation, have a side surface that is inclined and / or curved counter to the direction of rotation and pointing in the circumferential direction. It is particularly preferred if, in order to increase the efficiency of such a turbine-like drive, the side surfaces of the stator shear elements pointing in the circumferential direction are inclined and / or curved in the direction of rotation of the rotor, i.e. opposite to the previously described side surfaces of the shear elements of the rotor. In principle, it is sufficient if on the shear elements of the rotor and / or the stator only one side surface oriented in the circumferential direction is inclined as described, i.e. the front side surface in the direction of rotation or, alternatively, the rear side surface in the direction of rotation. However, optimum efficiency can be achieved if both side surfaces of the rotor shear elements and / or the stator shear elements, which are oriented in the circumferential direction, are correspondingly inclined and / or curved.

This means that, when looking along the axis of rotation from the inlet side in the direction of the outlet side, the rotation elements of the stator and the rotor are flat on the left side the shear elements are oriented counterclockwise in the direction of rotation during one revolution and the right side surfaces are oriented counter to the direction of rotation. In such a configuration, it is preferred if at least one of the side surfaces of the shear elements of the rotor is curved or inclined to the right, ie clockwise (viewed in the axial direction) and / or at least one of the side surfaces of the shear elements of the stator is to the left (ie in the direction of rotation of the rotor) is inclined or curved in order to achieve a corresponding propulsion or conveyance of milk and air.

It is very particularly preferred if the shear elements of the rotor and / or the stator, which are preferably at least partially contoured like turbine blades, are designed and present in such a number that with them a milk / air volume flow of 30 to 300 ml / min, in particular between 50 and 200 ml / min, very particularly preferably a volume flow of greater than 100 ml / min can be achieved, in particular at speeds of rotation of the rotor relative to the stator from a value range between 2000 rpm and 10000 rpm, particularly preferably between 5000 rpm and 7000 rpm.

In particular, if the milk frothing device is to be combined with a separate conveying device, in particular a pump, as part of a milk frothing system, in order to obtain higher degrees of freedom in the control (here then the conveyed quantity or the conveyed volume flow of the milk and the air is not or at least not exclusively depending on the rotational speed of the rotor), the shear elements can also be designed in such a way that they do not convey the milk and air essentially axially along the axis of rotation - here the circumferentially oriented side surfaces of the shear elements can lie in a radial plane, for example. It is also possible to use a preferably mirror-symmetrical (based on a radial mirror plane) tapering in the circumferential direction, for example by a convex or triangular contour design of the shear elements, in the axial direction to and fro forces acting on the milk and air, whereby the foaming result is improved and / or fewer shearing elements are used to achieve the same foaming result can.

It has been found to be particularly advantageous if the milk frothing device is designed as a flow heater, i.e. has integrated heating means, it being particularly expedient to integrate such heating means into the stator, in particular in the form of an electrical heater, for example a resistance heater. In the context of a milk foaming system comprising a milk foaming device according to the invention, separate heating means for heating the milk can then preferably be dispensed with.

In principle, it is possible, and provided within the scope of the further development of the invention, to supply milk and air to the emulsifying device already as a milk / air mixture, in particular through a single (common) supply line. However, an alternative embodiment is preferred, according to which separate supply lines for milk and air are provided, it being particularly useful if the milk line is assigned means for adjusting the throughput or the milk volume flow and / or the air supply line is assigned means for adjusting the air volume flow.

As already indicated, the invention also leads to a milk frothing system which has a beverage preparation device designed according to the concept of the invention with a ??? Milk frothing device comprises. With regard to the specific design of the milk frothing system, there are different options. According to a first alternative the milk frothing device is assigned separate conveying means for the milk from the shear elements, so that the milk volume flow through the emulsifying device can be adjusted independently of the speed of the rotation axis of the milk frothing device. According to an alternative design variant, such conveying means are deliberately dispensed with and the propulsion of the milk from a storage container to an outlet is generated solely by the design of the shear elements of the rotor and / or stator of the milk frothing device, in particular in the form of a turbine or with the help of acting or designed as turbine blades shear elements.

Depending on whether the milk frothing device has integral heating means, heating means separate from the milk frothing device for heating the milk can be dispensed with within the framework of the system. In principle, it is also possible to dispense with heating means entirely and / or to make it bypassable or switchable in order to be able to produce cold milk foam instead of hot or warm milk foam with the milk foaming device according to the invention.

In addition, the invention also leads to a method for frothing milk using a beverage preparation device according to the invention and / or a milk frothing system according to the invention, the invention providing that the milk and the air axially along the axis of rotation, the axially alternating shear elements of the rotor and the stator happens (and are sheared in the axially spaced shear gaps to produce milk foam).

As part of the process, the milk and the air are conveyed axially in a conveying direction along the axis of rotation from shear gap to shear gap or from inlet to outlet. In the event of the design of It is possible to use shear elements as turbine blades if this axial propulsion is brought about exclusively by rotation of the rotor.

In order to improve the foaming effect or the foam structure, it is particularly useful if the milk and air in the emulsifying chamber are subjected to force axially back and forth along the axis of rotation, in particular through a corresponding configuration of at least some of the shear elements, preferably all of the shear elements, whereby through the shear elements of the rotor and / or the stator preferably taper, in particular rounded or angularly, in the circumferential direction and are very particularly preferably designed mirror-symmetrically in this regard to a respective mirror plane through which the axis of rotation passes perpendicularly.

Further advantages, features and details of the invention emerge from the following description of preferred exemplary embodiments and on the basis of the drawings.

Fig. 1:

eine erfindungsgemäße Milchaufschäumvorrichtung von au-ßen,

Fig. 2 und 3:

Explosionsdarstellung der Milchaufschäumvorrichtung gemäß Fig. 1 aus unterschiedlichen Perspektiven, und

Fig. 4 bis Fig. 19:

unterschiedliche Gestaltungsvarianten von Scherelementkonturen zur Erzielung unterschiedlicher Schäum- und/oder Fördereffekte.

These show in:

Fig. 1:

a milk frothing device according to the invention from the outside,

Fig. 2 and 3:

Exploded view of the milk frothing device according to Fig. 1 from different perspectives, and

Fig. 4 to 19:

different design variants of shear element contours to achieve different foaming and / or conveying effects.

In the figures, the same elements and elements with the same function are identified by the same reference symbols.

In the Figs. 1 to 3 a milk frothing device 1 designed according to the concept of the invention is shown as part of a milk frothing system (not shown in detail) and a beverage preparation device (not shown in detail), in particular a coffee machine.

The milk frothing device 1 comprises an emulsifying device 2 which delimits or contains an emulsifying chamber 3. The emulsifying device 2 comprises a rotor 5 which can be rotated around an elongated axis of rotation R by means of an electric motor drive 4 and a stator 6 which surrounds the rotor 5 at a radial distance and is designed as a hollow body, which in the exemplary embodiment shown forms a housing 7 of the emulsifying device 2, more precisely the emulsifying chamber 3 .

Milk and air flow axially through the emulsifying device 2, starting from an inlet side 8 in the axial direction to an outlet side 9. The inlet side and outlet side 8, 9 of the emulsifying device are spaced apart along the axial extent of the axis of rotation. The outlet side 9 comprises a milk foam outlet channel 10, while the inlet side 8 has separate supply lines 11, 25 (cf. Fig. 1 ) for milk and air, of which in the Figures 2 and 3 only one milk supply line 11 is shown. The supply line 25 for air opens into the inlet side 8 at a distance from the supply line 11 in the circumferential direction. Alternatively, a milk / air mixture can also already be supplied through a single supply line.

The rotor 5 is inserted axially into the stator 6, the housing 7 on the outlet side from one containing the milk foam outlet channel 10 Cover 12 is closed, which is axially sealed relative to the stator 6 via an annular seal 13. A drive shaft 10 of the rotor 5 which coincides with the axis of rotation R is guided axially out of the stator 6 towards the in FIG Fig. 1 shown, axially adjacent to the housing 7 arranged drive 4.

It can now be seen that a total of six rows of shear elements 15 spaced apart from one another in the axial direction are arranged on the rotor 5, each of which extends in the circumferential direction around the axis of rotation R and each, here by way of example, comprises four shear elements 6 spaced apart in the circumferential direction, which are shown in FIG Embodiment by way of an injection molding process are formed in one piece with a rotor body 17, which is substantially cylindrically contoured and from which the rotor-side shear elements 16 extend outward in the radial direction.

In the circumferential grooves or axial gaps 18 between each two adjacent rows of shear elements 15 of the rotor 5, one of several rows of shear elements 19 of the stator 6 is arranged. Merely by way of example, the total of, for example, six shear element rows 19 of the stator 6 each include four circumferentially spaced (stator-side) shear elements 20, which here are formed in one piece with the housing 7 or a stator body 21 forming the housing 7 using the plastic injection molding process.

In the assembled state, in which the rotor 5 is located within the stator 6, the rows of shear elements 15 of the rotor 5 and the rows of shear elements 19 of the stator 6 alternate in the axial direction, i.e. in the axial direction along the axis of rotation R there is always a shear element side 15 on the rotor side a stator-side shear element row 19, so that between each shear element row 15 of the rotor 5 and each shear element row 19 of the stator 6 an axial and in element row 19 of the stator 6 an axial and circumferentially extending shear gap 22 is limited, in which the rotation of the rotor 5 about the axis of rotation R milk and air are sheared.

As will be explained later, a conveying device, in particular in the form of a milk pump, can be provided for conveying the milk / air volume flow or the foam, which is preferably arranged upstream of the milk frothing device 1 in the flow direction of the milk. If the shear elements 16 and / or 20 are designed as turbine blades, such a conveying device can possibly be dispensed with.

During operation, milk and air are supplied on the inlet side and the milk and air flow in the axial direction along the axis of rotation R to the outlet side 9, whereby, as can be seen, the inlet side 8 and outlet side 9 in the axial direction along the axis of rotation R for all rows of shear elements 15 , 19 of rotor 5 and stator 6 axially between them. This then leads to the fact that milk and air flow in the axial direction from the shear gap 22 to the shear gap 22 and alternately pass a row of shear elements 15 of the rotor and then a row of shear elements 19 of the stator 6 in the axial direction, through an area in the circumferential direction between two of the respective shear elements 16 and 20.

Based on Figures 4 to 19 different contour variants of shear elements 16, 20 are described below, which lead to different conveying and / or foaming effects. In all the figures, an arrow 23 indicates an axial flow direction of milk and air from an inlet side to an outlet side of the emulsifying device, this being shown in simplified form in each case in a development, namely in such a way that viewed inside in the plane of the drawing, to the right in following the axial flow direction (arrow 23), for example, a row of shear elements 19 of the stator 6 is followed by a row of shear elements 15 of the rotor 5, then again a row of shear elements 19 of the stator 6 and then again finally a row of shear elements 15 of the rotor 5, with further rows of shear elements 19, 15 in can connect in the axial direction. The rotor-side shear element rows 15 are marked with an arrow 24 for the direction of rotation, which makes it clear that the rotor 5 rotates in the present example in the counterclockwise direction.

It can also be seen that each shear element row 15, 19 has shear elements 16 and 20 spaced apart in the circumferential direction, the rotor-side shear elements 16 rotating relative to the stationary shear elements 20 by rotating the rotor 5 in the direction of the arrow 24. The above explanations relate to all Figures 4 to 19 which in this respect are structured analogously. It is also generally true for all the illustrated exemplary embodiments that the rotor-side shear elements 16 have an axial side V which is front in the axial flow direction 23 and a rear side H which is axially oriented in the opposite direction. The front V and rear H are connected to one another via circumferentially oriented and axially extending side surfaces S _V , S _H , the sides or side surfaces oriented with the reference symbol S _{V being} oriented in the direction of rotation 24, ie arranged at the front in the direction of rotation 24 and the side surfaces identified by the reference _{symbol S H} point against the direction of rotation 24. All the exemplary embodiments also have in common that the front and rear side surfaces V, H of both the shear elements 16 of the rotor 5 and the shear elements 20 of the stator 6 are rectilinear in the circumferential direction, or each lie in radial planes or coincide with them.

The differences between the various shear element contours of the exemplary embodiments according to FIGS Figures 4 to 19 explained.

the end Fig. 4 It can be seen that the side surfaces S _{H of} the rotor-side shear elements 16 viewed in the direction of arrow 24 over their entire axial extension are beveled in the plane of the drawing above, ie in the plane of rotation 24, while the opposite sides S _V lie in a radial plane or in an axial plane Direction are straight. The configuration of the stator-side shear elements 20 is exactly the opposite, ie the side surfaces S _V directed in the direction of rotation 24 of the rotor 5 are beveled in the direction of rotation 24, while the opposite side surfaces S _H are straight in the axial direction.

In the embodiments according to Figures 5 to 7 are more hydrodynamic contours with a similar effect as the embodiment according to FIG Fig. 4 realized. The side surfaces S _{V of} the stator-side shear elements 20 located in the direction of rotation 24 are concave or curved in the direction of the direction of rotation 24. The opposite side surfaces S _H are straight in the axial direction. In the rotor-side shear elements 16, a concave curvature in the direction of the direction of rotation 24 is also provided over their entire axial extent, namely in the side surfaces S _H oriented opposite to the direction of rotation 24, while the side surfaces S _V are straight in the axial direction. This then leads, analogously to Fig. 4 to the fact that the circumferential extent of the shear elements 16 of the rotor decreases in the arrow direction 23, while the circumferential extent of the shear elements 20 of the stator in the arrow direction 23 increases.

In Fig. 6 are the convex curvatures of the Fig. 5 has been replaced by concave curves, otherwise the same applies Fig. 5 Said analogously.

In the embodiment according to Fig. 7 The stator-side shear elements 20 taper with their side S _{V located} in the direction of rotation 24 in the direction of rotation 24, ie in the circumferential direction, specifically with convex radii of curvature. The shear elements 20 are designed to be mirror-symmetrical to a respective mirror plane S lying in a radial plane.

The shear elements 16 of the rotor 5 are contoured in opposite directions, that is, the side Sv in the direction of rotation 24 is straight in the axial direction and the opposite side S _H tapers against the direction of rotation 24, also with convex radii of curvature, with a mirror-symmetrical one here as well Training is given to a radial mirror plane.
This training leads to that, analogous to Fig. 10 , in the flow shadow of the rotor-side shear elements 16, the milk and air are subjected to force in opposing axial directions, so that there is an axial to-and-fro movement in the axial direction along the axis of rotation R, which coincides with the direction of the arrow 23, as shown in FIG the small arrows are indicated. Otherwise, the exemplary embodiment corresponds to FIG Fig. 10 according to the embodiment Fig. 7 , with the only difference that the convex curved tapers have been replaced by straight, arrow-shaped tapers. In the embodiment according to Fig. 11 The shearing elements 16, 20 taper in both circumferential directions, specifically by way of example with the arrow contour according to FIG Fig. 10 So that in addition to the flow shadow side in a front flow area there is an axial back and forth application of force to milk and air.

Fig. 8 shows an embodiment variant in which both the rotor-side shear elements 16 and the stator-side shear elements 20 are rectangularly contoured, that is to say they are continuously straight in the axial direction Have sides S _V and S _H. There is thus no fluid conveyance in the axial direction along the axis of rotation R.

The embodiment according to Fig. 9 corresponds to the embodiment according to Fig. 8 with the only difference that the axial extent of the shear elements 16, 20 has been reduced to save space - here the circumferential extent of the shear elements 16, 20 is significantly greater than their axial extent along the axis of rotation R.

The embodiment according to Fig. 12 corresponds exactly to the embodiment according to Fig. 4 Here, only additional small arrows are drawn, which show that milk and air are acted upon by force in different axial directions, ie back and forth in the manner of a shaking pump, this axial force application essentially occurring in the flow shadow of the rotating shear elements 16.

In the embodiment according to Fig. 13 the sides Sv are inclined against the direction of rotation 24 and their sides S _{H are} straight in the axial direction - this is the opposite for the rotor-side shear elements 16, i.e. the sides Sv are straight in the axial direction and the sides S _H are axially continuous against the direction of rotation 24 inclined, which also leads to the application of axial force and thus to an axial to-and-fro movement of the milk-air mixture.

In the embodiment according to Fig. 14 the formation or configuration of the stator-side shear elements 20 corresponds to that in connection with FIG Fig. 13 described construction of the shear elements 20 of the stator 6, so that the circumferential extent of the shear elements 20 decreases in the axial direction or in the flow direction. In contrast to the embodiment according to Fig. 13 are the side surfaces S _H the rotor-side shear elements 16 inclined in the direction of rotation 24, so that the circumferential extent of the shear elements 16 decreases in the axial direction. This then leads to a force application of the milk / air in the opposite direction to the flow direction 23, so that a separate pump must be provided here which conveys the milk in the direction 23 The contour or geometry of the shear elements 16, 20, the flow direction 23 results.

In the embodiment according to Fig. 15 the configuration of the stator-side shearing elements 20 corresponds to that according to FIG Fig. 4 , wherein the configuration or geometry of the rotor-side shear elements 16 that according to FIG Fig. 13 corresponds, ie their circumferential extent increases in the axial conveying direction 23, since the sides S _H are angled against the flow direction 24 (while the sides S _{V are} straight and the sides S _{V of} the stator-side shear elements 20 are inclined in the direction of rotation 24 and their sides S _{H are designed} to be straight in the axial direction).

In Fig. 19 a configuration as a turbine or pump is also shown, ie the arrangements of the Figures 15, 19 ensure that milk and air are conveyed in the conveying direction 23, which means that an additional conveying pump can be dispensed with if necessary. While the corresponding axial force application of the fluid in the configuration according to FIG Fig. 15 essentially results in the flow shadow of the shear elements 16, is in the configuration according to FIG Fig. 19 A corresponding force application is also given on the opposite side of the shear elements 16, 20 in the circumferential direction, which is due to the fact that, in contrast to Fig. 15 the sides S _{H of} the stator-side shear elements 20 are also inclined in the direction of rotation 24, here parallel to the associated sides S _V. The sides S _{V are also} the rotor-side shear elements 16 inclined against the direction of rotation 24, just like their sides S _H.

The embodiment according to Fig. 18 corresponds to the embodiment according to Fig. 19 with the difference that the direction of inclination of all the shear elements 16, 20 is implemented in exactly the opposite direction, which results in a relatively strong flow effect opposite to the flow direction 23, which must be compensated for or overridden by the provision of a corresponding pump.

In the embodiment according to Fig. 17 the configuration or geometry of the rotor-side shear elements 16 corresponds to that of the exemplary embodiment according to FIG Fig. 19 , while the geometry of the stator-side shear elements 20 that of the stator-side shear elements 20 according to FIG Fig. 18 corresponds, that is, both sides S _V , S _H are inclined against the direction of rotation 24, both in the shear elements 16 of the rotor 5 and the shear elements 20 of the stator 6, which again leads to a shaking pump effect and milk and air are axially force-impacted back and forth .

In the embodiment according to Fig. 16 the direction of inclination of the shear elements 16, 20 is exactly the opposite of that in the exemplary embodiment according to FIG Fig. 17 , ie the configuration or contour of the rotor-side shear elements 16 corresponds to that according to the exemplary embodiment shown in FIG Fig. 18 , while the stator-side shear elements 20, as in the embodiment according to Fig. 19 shown, are contoured, ie the sides Sv, S _{H of} the stator-side shear elements 20 are inclined in the direction of rotation 24, as well as the side surfaces S _V , S _{H of} the rotor-side shear elements 16, which also results in a force application of milk and air in opposite axial directions .

Reference number

1

Milk frother

2

Emulsifying device

3

Emulsification chamber

4th

drive

5

rotor

6th

stator

7th

casing

8th

Inlet side

9

Outlet side

10

Milk foam outlet duct

11

Feed line for milk

12th

lid

13th

Ring seal

14th

wave

15th

Rows of shear elements of the rotor

16

Shear elements of the rotor

17th

Rotor body

18th

Axial gaps

19th

Rows of shear elements of the stator

20th

Shear elements of the stator

21

Stator body

22nd

Shear gap

23

Arrow (axial conveying direction along the axis of rotation)

24

Arrow (direction of rotation in the circumferential direction around the axis of rotation)

25th

Supply line for air

R.

Axis of rotation

V

front

H

Rear

SV

(circumferential) sides of the shear elements pointing in the direction of rotation

SH

(circumferential) sides of the shear elements pointing against the direction of rotation

S.

Mirror plane

Claims (14)

1. A coffee machine comprising a milk frothing device (1), wherein the milk froth is addable to another beverage component, namely to coffee, and wherein the coffee machine has an injection unit for leaching and/or dissolving beverage substrate provided in beverage substrate capsules or an integral grinder and a brewing unit in which coffee grounds produced from coffee beans by the integral grinder is leached, and wherein the milk frothing device (1) having a mechanical emulsification device (2) comprises a stator (6) and a rotor (5) which can be driven to rotate relative to said stator (6) around a rotation axis (R), wherein milk and air can be supplied to said emulsification device via the inlet side and exposed to shearing forces by means of the rotation of the rotor (5) relative to the stator (6), whereby milk froth is produced, said milk froth being removable via the outlet side, and the rotor (5) as well as the stator (6) having a plurality of shear element rows (15, 19) comprising shear elements (16, 20) for generating the shearing forces, wherein the shear element rows (15) of the rotor (5) and the shear element rows (19) of the stator (6) mesh in such an intermitting manner that milk and air flowing through the intermitting shear element rows (15, 19) are each shearable between one of the shear element rows (15) of the rotor (5) and one directly adjacent shear element row (19) of the stator (6) during rotation of the rotor (5),
   characterized in that
   the shear element rows (15) of the rotor (5) and the shear element rows (19) of the stator (6) are arranged alternately along the rotation axis (R).
2. The coffee machine according to claim 1,
   characterized in that
   the shear element rows (15) of the rotor (5) each comprise a plurality of shear elements (16, 20) spaced apart in the circumferential direction around the rotation axis (R), said shear elements extending in the radial direction, in particular from radially inwards to radially outwards, from a rotor body (17) of the rotor (5), which extends along the rotation axis (R), in such a manner that the milk and the air each flow in the axial direction along the rotation axis (R) between two of the shear elements (16) adjacent to each other in the circumferential direction to the shear element row (19) of the stator (6) adjacent in the axial direction and/or that the shear element rows (19) of the stator (6) each comprise a plurality of shear elements (20) spaced apart in the circumferential direction around the rotation axis (R) and extending in the radial direction, in particular from radially outwards to radially inwards, from a stator body (21) of the stator (6), which preferably has a hollow cylindrical shape and extends along the rotation axis (R), in such a manner that the milk and the air each flow in the axial direction along the rotation axis (R) between two of the shear elements (20) adjacent to each other in the circumferential direction to the shear element row (19) of the rotor (5) adjacent in the axial direction.
3. The coffee machine according to claim 1 or 2,
   characterized in that
   an inlet side (8) for milk and air and an outlet side (9) for milk froth are spaced apart axially along the rotation axis (R) across the majority of the shear element rows (15, 19), in particular across all shear element rows (15, 19).
4. The coffee machine according to any one of the preceding claims,
   characterized in that
   the preferably cylindrical emulsification device (2) is shaped in an elongated manner and comprises a longitudinal dimension that is larger than, preferably twice as large as, further preferably at least three times as large as, a diametrical dimension measured perpendicularly thereto along the rotation axis (R).
5. The coffee machine according to any one of the preceding claims,
   characterized in that
   at least some, preferably all of the shear elements (16) of at least some, preferably of all of the shear element rows (15) of the rotor (5) and/or at least some, preferably all of the shear elements (20) of at least some, preferably of all of the shear elements rows (19) of the stator (6) are contoured in such a manner that the milk and the air are transportable through the emulsification device (2) in the axial direction along the rotation axis (R) by means of the rotation of the rotor (5).
6. The coffee machine according to any one of the preceding claims,
   characterized in that
   for the axial transport of the milk and air, the emulsification device (2) is configured as a turbine and at least some of the shear elements (16, 20) of the rotor (5) and/or of the stator (6) are configured as turbine blades, in particular as turbine blades that are curved or sloped in relation to the rotation axis (R).
7. The coffee machine according to any one of the preceding claims,
   characterized in that
   at least some, preferably all of the shear elements (16), of at least some, preferably of all of the shear element rows (15) of the rotor (5) and/or at least some, preferably all of the shear elements (20) of at least some, preferably of all of the shear element rows (19) of the stator (6) are contoured in such a manner that the milk and the air can be subjected to a force, in particular transported, back and forth in the axial direction along the rotation axis (R) or not be transported in the axial direction along the rotation axis (R).
8. The coffee machine according to any one of the preceding claims,
   characterized in that
   the milk frothing device (1) comprises integrated heating means, in particular integrated into the stator (6).
9. The coffee machine according to any one of the preceding claims,
   characterized in that
   a joint supply line, in particular one singular joint supply line, for a milk-air-mixture comprising the milk and the air is provided on the inlet side, or that separate supply lines (11, 25) for milk and air open into the emulsification device, said supply lines preferably being equipped with means for varying a milk volume flow and/or an air volume flow.
10. The coffee machine according to any one of the preceding claims,
    characterized in that
    the milk frothing device is connected in a fluid-conducting manner to a milk supply line and an air supply line of the coffee machine.
11. A milk frothing system comprising a coffee machine according to any one of the preceding claims, wherein according to a first alternative transport means for milk are assigned to the milk frothing device (1), by means of which milk is transportable from a storage container in the axial direction through the emulsification device or, according to a second alternative, no transport means separate from the milk frothing device (1) are provided for transporting the milk through the emulsification device and the transport of the milk through the emulsification chamber is realized, in particular exclusively, by accordingly designed shear elements (16, 20) of the milk frothing device (1).
12. A method for frothing milk using a coffee machine according to any one of claims 1 to 10 and/or a milk frothing device according to claim 11, wherein milk and air are transported through a mechanical emulsification device comprising a stator (6) and a rotor (5) which can be driven to rotate relative to said stator (6) around a rotation axis (R), wherein shear element rows (15) of the rotor (5) and shear element rows (19) of the stator (6) mesh in such an intermitting manner that milk and air flowing through the intermitting shear element rows (15, 19) are each sheared between one of the shear element rows (15) of the rotor (5) and one directly adjacent shear element row (19) of the stator (6) during rotation of the rotor (5),
    characterized in that
    the shear element rows (15) of the rotor (5) and the shear element rows (19) of the stator (6) are arranged alternately along the rotation axis (R), and thus the milk and the air pass the alternately arranged shear element rows (15, 19) of the rotor (5) and of the stator (6) in the axial direction along the rotation axis (R).
13. The method according to claim 12,
    characterized in that
    the milk and the air are transported through the emulsification device in the axial direction, in particular exclusively by means of the rotation of the rotor (5) or by means of a separate transport device.
14. The method according to claim 12 or 13,
    characterized in that
    milk and air are subjected to a force back and forth and preferably move back and forth in the axial direction along the rotation axis (R) in the emulsification chamber.

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